In modern paint plants for painting motor vehicle body components rotary atomisers which have a rotating bell cup as the spray body are generally used as the application device. In general the bell cup is mounted by means of a screw-type connection to the bell cup shaft of the rotary atomiser, the releasable screw-type connection allowing the bell cup, which is regularly removed for cleaning purposes, to be replaced when it is worn. The screw-type connection also centres the bell cup in the hollow turbine shaft.
A drawback of this conventional bell cup attachment by means of a screw-type connection is the soiling tendency of the external thread of the bell cup and of the internal thread of the bell cup shaft. This is particularly problematic as cleaning these threads takes a great deal of time.
A further disadvantage of the conventional bell cup attachment is that for screwing on the bell cup at least five rotations of the bell cup relative to the bell cup shaft are typically required in order to form a strong screw connection. When replacing the bell cup for cleaning or due to wearing a respective number of rotations of the bell cup relative to the bell cup shaft is also required in order to release the bell cup from the bell cup shaft.
Moreover, with the conventional bell cup attachment by means of screwing, there is the risk of the bell cup unintentionally becoming detached in the event of sudden braking of the bell cup during blocking of the bearing unit, which given the high speeds of around 8000-80,000 revs/min achieved during operation, can be extremely dangerous.
Furthermore, soiling of the bell cup thread may lead to a mechanical imbalance which is associated with corresponding mechanical stressing of the bearing unit and in extreme cases can result in failure of the bearing unit.
Finally, with the conventional bell cup attachment by means of screwing, there is a risk of the bell cup thread becoming jammed and thereby blocked. Removal of the bell cup is then no longer possible.
Accordingly, there is a need for an improved bell cup attachment.